Eeeeeeeeeeeeeeeeew! This is absolutely repulsive. I have a step niece who similarly shows rather shockingly 'intimate' behaviour with her mother - but she is only 17 - which I find disgustingly and uncomfortably inappropriate. I watch her too climb upon her mother and nuzzle her chest as though she were a toddler. It is inappropriate and very off-putting - especially when this goes on for hours. How does my sister-in-law allow this to happen, especially in public (and if the girl will behave this way in public how does she behave privately). Just gross. I can't imagine seeing a boy do this with his mother.

Does this woman encourage it? What is her own reaction to this? Does she welcome it or merely put up with it?

I agree with you that there is something not right here but I would not point to narcissism or aspergers. This goes deep. Perhaps there has been an event precipitating this behaviour.

In the case of my step-niece she does have mental health issues causing very significant delusions (she once tried to jump off a bridge at age 14). What the diagnosis is I do not know but I view the weirdly uncomfortably inappropriate behaviour as an instinctual safety response. The girl obviously finds such behavior emotionally comforting. I don't think it is about wanting physical contact at all rather a craving for a safe place.

Does any of this remind you of the situation you describe?